First off, be
warned: this is not a new tutorial on how to make
and use a func_areaportal. If you need to know
how to make one, check out fishman's tutorial on that very thing.

Now, the purpose of this
mini-tutorial is to familiarize you with one of
the problems you will almost undoubtedly come
across when you are using func_areaportals: the
dreaded "func_areaportal <entity
number> doesn't touch two areas"
error. Don't worry, it's a pretty simple thing.

A
func_areaportal must entirely separate two areas.
That's it; it's that simple. This means that
there can be no "leaks" (for lack of a
better word) between the areas on either side of
the areaportal. Anything that does not
completely block vis, such as windows, holes,
func_walls, detail brushes, transparent brushes,
brushes with the mist flag set, liquid, etcetera,
etcetera, will generate the error if
that brush or entity connects the two areas. If,
on the other hand, another func_areaportal is
used, the error is gone. Makes sense, because the
very purpose of the areaportal is to block vis.

What it all boils
down to is this: If you get this error, make
sure that the only way for you or the engine to
get (or see) from one side of an areaportal to
the other, is through an areaportal
(doesn't have to be the same one.)

Another
little thing, and a bonus for sitting through my
feeble attempt at coherency:

func_areaportals and multi-part
doors. (WooHoo! Excited?) There are a few ways to do muti-part
doors, and this is just one. One of the doors in the
example map is a two-part door, for reference.

Quick and simple.
First, create your door, and place one areaportal
inside the doorway, just like the door was one
piece. Now, give all of the pieces of the door a
matching "team" key. For example,
"door1". Now all of your door pieces
have "team"="door1". Next
step: set one of the door pieces to target the
areaportal. Thats it.

There are a few
good things about this. First, you won't have to
worry about one side of a door triggering the
areaportal off, and the other trigering it back
on. Second, in the case of an especially wide
door, no matter how you approach the door, it
will always open all at once.

-GrrandMaMa

You can download the [example .map] here. Also if you have any problems or need some
help please post to the discussion board.